Cherokee Six Weight & Balance Calculator
Ensure Safe Flight Operations for Your Piper PA-32 Series Aircraft
Aircraft Weight & Balance Calculation
Calculation Results
Total Weight = Sum of all individual weights.
Total Moment = Sum of individual moments (Weight x Arm).
Center of Gravity (CG) = Total Moment / Total Weight.
Weight & Balance Envelope
Chart showing the calculated CG against the allowable weight and CG limits.
What is Cherokee Six Weight & Balance?
The Cherokee Six Weight & Balance calculation is a critical process for pilots operating Piper PA-32 series aircraft. It involves determining the aircraft's total weight and the location of its center of gravity (CG) for a specific loading condition. Ensuring the aircraft is within its certified weight and balance limits is paramount for flight safety. An out-of-balance aircraft can be unstable, difficult to control, and in extreme cases, lead to loss of control or structural failure. This calculation is not just a regulatory requirement; it's a fundamental aspect of safe aviation practice.
Who should use it: Any pilot or operator preparing to fly a Cherokee Six (PA-32-260, PA-32-300, PA-32RT, PA-32-R, etc.) needs to perform this calculation. This includes private pilots, commercial operators, flight instructors, and aircraft maintenance personnel involved in loading.
Common Misconceptions:
- "It's just a formality": Weight and balance directly impacts aircraft stability and performance. It's a crucial safety check.
- "My aircraft feels fine, so it must be balanced": Subjective feel can be misleading. Aerodynamic forces and control effectiveness can be significantly altered by an improper CG, even if the aircraft is still controllable.
- "If it's within the useful load, it's fine": Useful load only addresses the total weight limit. The CG position is equally important and must be within the forward and aft limits.
- "The book numbers are close enough": Exact weights of passengers, baggage, and fuel, along with their precise locations (arms), are necessary for an accurate calculation.
Cherokee Six Weight & Balance Formula and Mathematical Explanation
The calculation of weight and balance for a Cherokee Six involves summing up the weights and moments of all components and then determining the resulting Center of Gravity (CG).
The Core Formulas:
1. Moment Calculation: For each item (aircraft empty weight, fuel, passengers, baggage), the moment is calculated by multiplying its weight by its horizontal distance from the aircraft's datum (arm).
Moment = Weight × Arm
2. Total Weight Calculation: All individual weights are summed to find the aircraft's total weight.
Total Weight = Σ (Individual Weights)
3. Total Moment Calculation: All individual moments are summed to find the aircraft's total moment.
Total Moment = Σ (Individual Moments)
4. Center of Gravity (CG) Calculation: The total moment is divided by the total weight to find the CG location.
CG = Total Moment / Total Weight
Variable Explanations:
The inputs required for the Cherokee Six weight and balance calculation are:
| Variable | Meaning | Unit | Typical Range / Notes |
|---|---|---|---|
| Basic Empty Weight (BEW) | The weight of the aircraft with all standard equipment installed, but without crew, passengers, usable fuel, or baggage. | lbs | ~1800 – 2200 lbs (Varies by model and equipment) |
| BEW Datum Arm | The horizontal distance from the aircraft's datum line to the CG of the empty weight. | inches | ~80.0 – 90.0 inches (Refer to POH) |
| Useful Load | The maximum allowable weight of the pilot, passengers, baggage, and usable fuel. | lbs | ~1000 – 1400 lbs (Refer to POH) |
| Usable Fuel Weight | The weight of the fuel that can be used during flight. (Fuel Weight = Usable Fuel Volume × Fuel Density) | lbs | ~0 – 400 lbs (Standard tanks hold ~84 gal, ~504 lbs total; usable depends on fuel burn). 6 lbs/gallon is common. |
| Front Passenger Weight | Combined weight of the pilot and front seat passenger. | lbs | ~150 – 400 lbs (e.g., 2 x 170 lbs) |
| Rear Passenger Weight | Combined weight of passengers in the rear seats. | lbs | ~150 – 500 lbs (e.g., 3 x 170 lbs) |
| Baggage Weight | Weight of luggage or cargo in the baggage compartment. | lbs | ~0 – 100 lbs (Weight limits apply to specific baggage areas) |
| Datum Arms (Fuel, Passenger, Baggage) | Horizontal distances from the datum to the CG of each respective load item. | inches | Vary by location (e.g., Fuel: ~85.0, Front Pass: ~78.0, Rear Pass: ~95.0, Baggage: ~118.0 – Refer to POH) |
| Minimum Allowable CG | The forward limit of the aircraft's CG range. | inches | Typically ~75.0 – 77.0 inches (Refer to POH) |
| Maximum Allowable CG | The aft limit of the aircraft's CG range. | inches | Typically ~88.0 – 90.0 inches (Refer to POH) |
Practical Examples (Real-World Use Cases)
Example 1: Standard Day Flight
A pilot is preparing for a local flight in their Piper PA-32-300 Cherokee Six. They plan to carry themselves (180 lbs), one passenger (160 lbs), and a moderate amount of baggage (70 lbs). They intend to load 40 gallons of usable fuel (approx. 240 lbs). They consult their aircraft's Pilot's Operating Handbook (POH) for the datum arms and limits.
Assumed POH Data:
- BEW: 2050 lbs
- BEW Arm: 85.0 in
- Useful Load: 1300 lbs
- Fuel Density: 6.0 lbs/gallon
- Fuel Arm: 85.0 in
- Front Passenger Arm: 78.0 in
- Rear Passenger Arm: 95.0 in
- Baggage Arm: 118.0 in
- Min CG: 75.5 in
- Max CG: 88.5 in
Inputs:
- Empty Weight: 2050 lbs
- Empty Arm: 85.0 in
- Useful Load: 1300 lbs
- Usable Fuel Weight: 240 lbs (40 gal * 6 lbs/gal)
- Front Passenger Weight: 340 lbs (180 + 160)
- Rear Passenger Weight: 0 lbs
- Baggage Weight: 70 lbs
Calculation Using Calculator:
- Total Weight: 2050 (BEW) + 240 (Fuel) + 340 (Pax) + 70 (Baggage) = 2700 lbs
- Total Moment: (2050 * 85.0) + (240 * 85.0) + (340 * 78.0) + (70 * 118.0) = 174250 + 20400 + 26520 + 8260 = 229430 lb-in
- CG: 229430 lb-in / 2700 lbs = 85.0 in
Result Interpretation: The calculated total weight of 2700 lbs is well below the typical useful load limit. The CG of 85.0 inches falls within the allowable range of 75.5 inches (forward) to 88.5 inches (aft). This loading is safe.
Example 2: Fully Loaded Trip with Longer Range Fuel
The same pilot is planning a longer trip and decides to fill the tanks with 84 gallons of usable fuel (~504 lbs). They will carry two 170 lb passengers in the front and two 160 lb passengers in the rear, plus 100 lbs of baggage.
Inputs:
- Empty Weight: 2050 lbs
- Empty Arm: 85.0 in
- Useful Load: 1300 lbs
- Usable Fuel Weight: 504 lbs (84 gal * 6 lbs/gal)
- Front Passenger Weight: 340 lbs (170 + 170)
- Rear Passenger Weight: 320 lbs (160 + 160)
- Baggage Weight: 100 lbs
Calculation Using Calculator:
- Total Weight: 2050 (BEW) + 504 (Fuel) + 340 (Front Pax) + 320 (Rear Pax) + 100 (Baggage) = 3314 lbs
- Total Moment: (2050 * 85.0) + (504 * 85.0) + (340 * 78.0) + (320 * 95.0) + (100 * 118.0) = 174250 + 42840 + 26520 + 30400 + 11800 = 285810 lb-in
- CG: 285810 lb-in / 3314 lbs = 86.24 in (approx.)
Result Interpretation: The calculated total weight of 3314 lbs exceeds the typical useful load limit of 1300 lbs (BEW is 2050 lbs, so max takeoff weight is around 3350 lbs, meaning there is very little margin for passengers and fuel). The CG of 86.24 inches is within the acceptable range (75.5 to 88.5 inches). However, the pilot must verify that the total takeoff weight does not exceed the aircraft's maximum gross weight (typically around 3350 lbs for a PA-32-300). In this scenario, there is minimal margin, highlighting the importance of precise loading.
How to Use This Cherokee Six Weight & Balance Calculator
Using this calculator is straightforward and designed to provide quick, accurate results. Follow these steps to ensure your Cherokee Six is properly loaded for every flight.
- Gather Aircraft Data: Locate your Cherokee Six's Pilot's Operating Handbook (POH) or Weight & Balance manual. You'll need the Basic Empty Weight (BEW), the Datum Arm for the BEW, and the allowable CG range (minimum and maximum CG).
- Gather Loading Data: Accurately determine the weight of everything that will be added to the aircraft: usable fuel, passengers (pilot included), and baggage. Know the specific location (arm) for each item as specified in your POH. If you are unsure of specific passenger weights, use conservative estimates or actual weights if known.
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Enter Data into Calculator: Input the gathered data into the corresponding fields on the calculator:
- 'Basic Empty Weight (BEW)'
- 'BEW Datum Arm'
- 'Useful Load' (Note: This is the maximum allowable for *all* added items, not a value to input directly for calculation, but good to know for context).
- 'Usable Fuel Weight'
- 'Front Passenger Weight' (Pilot + Front Seat Passenger)
- 'Rear Passenger Weight' (All passengers in rear seats)
- 'Baggage Weight'
- 'Datum Arms' for Fuel, Front Passenger, Rear Passenger, and Baggage.
- 'Minimum Allowable CG' and 'Maximum Allowable CG' from your POH.
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Review Results: As you enter data, the calculator will automatically update the results:
- Primary Result (CG): This is the calculated Center of Gravity for your current loading.
- Total Weight: The total weight of the aircraft with the loaded items.
- Total Moment: The sum of all moments.
- Loading Status: This will indicate if your calculated CG is within the allowable limits (Normal, Forward CG Limit, Aft CG Limit).
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Interpret the Results:
- Check Total Weight: Ensure the 'Total Weight' does not exceed the aircraft's maximum gross weight (typically found in the POH, often around 3350 lbs for a PA-32-300).
- Check CG: The primary 'CG' result must fall between the 'Minimum Allowable CG' and 'Maximum Allowable CG' entered. The 'Loading Status' will clearly indicate this.
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Adjust Loading if Necessary: If the total weight or CG is out of limits, you must adjust the loading. This might involve:
- Reducing the amount of fuel.
- Shifting baggage weight.
- Adjusting passenger load.
- Considerations about the passenger locations relative to the datum arms.
- Use the Chart: The dynamic chart visually represents your current loading (Total Weight and CG) against the aircraft's weight and balance envelope. This provides an immediate understanding of your position relative to the safe operating limits.
- Reset or Copy: Use the 'Reset Defaults' button to clear current entries and start fresh. Use the 'Copy Results' button to easily transfer the calculated values and assumptions for your records.
Decision-Making Guidance: Always err on the side of caution. If your calculation is borderline, consider making adjustments to ensure a comfortable margin within the CG limits. Never rely solely on previous calculations; perform a fresh weight and balance for every flight, especially if the loading differs from previous flights. Accurate weight and balance is fundamental to safe flight operations in your Cherokee Six.
Key Factors That Affect Cherokee Six Weight & Balance Results
Several factors significantly influence the weight and balance of your Cherokee Six. Understanding these elements is key to performing accurate calculations and ensuring safe flight:
- Basic Empty Weight (BEW) and its Arm: The BEW is the foundation of your calculation. Any changes to the aircraft's equipment (e.g., installing new avionics, de-icing boots, or optional seating) will alter the BEW and potentially its center of gravity arm. It's crucial to keep your aircraft's weight and balance records updated to reflect these modifications. A heavier BEW means less capacity for useful load.
- Fuel Load: Fuel is often the most variable component of weight and balance. The density of fuel (e.g., Avgas vs. Jet A, or variations in Avgast) affects its weight per gallon. More importantly, the amount of fuel loaded directly impacts total weight and the CG position. Loading full tanks significantly shifts the CG aft compared to loading just enough for a short flight, especially if the fuel tanks' arms are aft of the datum. Planning fuel stops can be essential for maintaining balance on longer trips.
- Passenger and Baggage Loading: The weights of passengers and baggage, and critically, their placement within the cabin and baggage compartments, have a substantial effect. Passengers in the aft seats or baggage loaded in the furthest rear compartment will move the CG aft. Conversely, heavier passengers or baggage loaded forward will move the CG forward. Uneven distribution can also introduce undesirable moments.
- Aircraft Configuration and Optional Equipment: The specific model of the Cherokee Six (e.g., PA-32-260 vs. PA-32-300, fixed gear vs. retractable gear) has different standard weights and CG ranges. Furthermore, modifications like auxiliary fuel tanks, different seating configurations (e.g., 6 vs. 7 seats), or cargo pods will alter the aircraft's weight and balance characteristics. Always refer to the specific POH for your aircraft's configuration.
- Datum and Arm Accuracy: The datum line is an arbitrary reference point from which all horizontal measurements (arms) are taken. The accuracy of the datum itself, and the precise measurement of the arm for each weight item, is fundamental. Small errors in arm measurements can lead to significant errors in the calculated CG, especially for heavy items located far from the datum.
- Environmental Factors (Indirectly): While not directly part of the CG calculation, factors like temperature and altitude can influence aircraft performance, which might affect flight planning and thus the amount of fuel required. For instance, higher altitudes require more airspeed for takeoff and climb, which can influence fuel burn rates. This indirectly affects how much fuel you'll load and thus the weight and balance. Also, consider the weight of optional external equipment like skis or floats if applicable.
- Calculation Method and Precision: Using the correct formula and ensuring all intermediate calculations are precise is vital. Rounding too early can lead to inaccuracies. Employing a reliable calculator like this one, or meticulously following the manual's procedures, minimizes calculation errors. Double-checking the input values before calculation is also a key step.
Frequently Asked Questions (FAQ)
A: The CG range varies slightly by specific model (PA-32-260, PA-32-300, etc.) and any modifications. Typically, the forward limit is around 75.0-77.0 inches aft of the datum, and the aft limit is around 88.0-90.0 inches aft of the datum. Always refer to your aircraft's specific POH for precise limits.
A: Standard tanks hold approximately 84 gallons of usable fuel. With a typical fuel density of 6.0 lbs/gallon, this equates to about 504 lbs. The exact weight will depend on the actual fuel density and how much usable fuel is loaded.
A: The maximum takeoff weight also varies by model. For many PA-32-300 variants, it's around 3350 lbs. The POH will specify the exact maximum gross weight. Your calculated Total Weight must not exceed this.
A: It depends on their weights and the amount of fuel. With 6 adults averaging 170 lbs each (1020 lbs total), plus the pilot (say 180 lbs), that's 1200 lbs for passengers alone. Combined with fuel and baggage, it's very likely to exceed the useful load or even the maximum gross weight, or place the CG outside limits. Careful calculation is mandatory.
A: Flying an aircraft outside its CG limits can severely affect its stability and controllability. Forward CG can make the aircraft difficult to rotate for takeoff and may require excessive force to flare for landing. Aft CG can make the aircraft unstable, susceptible to stalls, and difficult to recover from unusual attitudes. It is dangerous and prohibited.
A: You must perform a weight and balance calculation for every flight, especially if the loading configuration (fuel, passengers, baggage) changes from the previous flight. Significant maintenance or equipment changes also require an updated weight and balance computation.
A: BEW typically includes standard equipment, fixed ballast, and unusable fuel/oil. Operating Empty Weight (OEW) is BEW plus standard operating items like 5 gallons of oil, and pilot/crew seats. For many calculations, BEW is the starting point, and specific POH procedures dictate what to include.
A: The most accurate source is your aircraft's official Pilot's Operating Handbook (POH) or Flight Manual. Weight and balance information is also usually detailed in the aircraft's Weight and Balance Record or Logbook.